> I'm starting to record surround sound alongside with panoramic videos. On=
e of the sample MP4's has an audio file structure of
>
> 0L.wav
> 0R.wav
> 90L.wav
> 90R.wav
> 180L.wav
> 180R.wav
> 270L.wav
> 270R.wav
>
> Have any of you seen this structure
Where did that sample come from? I've never seen those track names. Looks l=
ike degrees of azimuth, but what are two at zero and 180?
> and if so, how are these signal sources positioned (i.e. is 90L/R on the =
right or on the left when looking down on it)? How are they recorded (I'm a=
ssuming 4 pairs of stereo mics)? And most importantly, how are they process=
ed, edited and embedded into the mp4 file so that they are positionally cor=
rect?
They don't make sense to me, I'd just be guessing. Ask the source.
There are three different standard sequences for surround channels on the r=
ecorder and studio console, Dolby, DTS, and I think SMPTE. I'm not sure whe=
ther encoding of the output goes by the channel names or sequence. When I m=
ade a surround DVD I let the authoring software (Apple Final Cut Pro and Co=
mpressor) encode the audio channels so I don't know what happened there. I =
wouldn't be surprised if authoring software has a preference to set for you=
r preferred working sequence. Obviously the output medium has a standard ch=
annel sequence. I'd use the Dolby sequence.
> If any of you have worked with this kind of format I'd be very thankful i=
f you could give me a hint for where to start.
I've been recording soundscapes in surround for many years, using the stand=
ard Dolby channel names L, R, Ls, Rs. I use a technique described by former=
list subscriber Rich Peet:
Your favorite stereo array for L and R
Omni mics spaced 40' to the left and 40' to the right for Ls and Rs.
Thus the front pair is imaging and the rear pair are uncorrelated (very muc=
h so, 80' apart).
I use a Jecklin Disk for my front array thus four identical omni mics in th=
e system.
The original Rich Peet technique is great for being on a trail. It only rev=
eals its "defective" geometry when a jogger comes through! In an open space=
I usually pull the rears back 20' or so. Or position them opportunisticall=
y, like that bunch of trees there and those bushes.
Steve Sergeant, a nature recordist who works at Dolby, has been encouraging=
us to add height channels to our recordings. I've done it once but I don't=
have proper playback set up yet to evaluate it. The minimum would be a ste=
reo pair raised say 14', axis left and right, pointing up. A bit of a hardw=
are challenge.
The LFE channels is created in production when desired, there is no need to=
record an LFE channel in the field.
I like time-space in my recordings and rarely use one-point techniques.
-Dan
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